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A370660
Numbers k such that (7^k + 7*k)/7 is prime.
2
1, 4, 36, 160, 342, 1086, 2094, 11524
OFFSET
1,2
COMMENTS
If it exists, a(11) > 50000.
PROG
(PARI) is(n) = ispseudoprime(7^(n-1)+n)
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Hugo Pfoertner, Feb 24 2024
STATUS
approved